The present invention relates to an auto-expansible cushioning bag useful in the field of wrapping, insulation and the filling of cavities, by means of cushioning, insulating or filling materials.
More particularly the invention has for its object the provision of such a bag which is useful e.g. for protectively embedding fragile articles and other purposes.
For filling and packaging, generally straw, foam waste, wood shavings or the like are used. Likewise for the insulation of pipes or conduits it is usual to surround these with insulating materials such as glass wool or rock wool. However these insulating, filling and packaging processes most frequently involve a significant generation of dust, and therefore have a soiling effect, and necessitate relatively great expense for their utilization.
To diminish these drawbacks it has been proposed to utilize polyurethane foam in the form of rigid or semi-rigid half-shells, or again to cast the said polyurethane foam in situ.
Thus it is possible to pack an object in sandwich fashion between two half-shells which have each been provided during manufacture with a half impression of the object to be packed, the cushioning of which is thus effected in a cocoon of foam made to measure. The insulation of a pipe will be effected in the same manner, by enveloping the pipe between two half-shells the cavities of which are molded to the form and dimensions of the pipe to be insulated.
In the case of packaging by in situ casting, the object to be packed is previously placed in a hermetic bag of polyethylene, then is introduced into a wooden or cardboard box, and a foaming mixture of polyurethane is cast, with the aid of a special machine, into the said box. This mixture then expands and polymerizes, intimately surrounding the object in its lower and lateral parts. After this first operation the covering of the upper part of the object is effected by a second casting in such manner as to imprison the object entirely in a cocoon of foam. The insulation of pipes is effected in the same manner, with the exception however of the provision of a shuttering around the pipe, serving as temporary receptacle for the foam. The process of in situ casting of the polyurethane foam is furthermore of relatively great interest for the filling of the cavities of hollow bodies for the purpose of their thermal and/or acoustic insulation or their solidification.
However, in the case of insulation or packaging between two rigid or semi-rigid half-shells, it is necessary to create a special and costly mold for each object to be packed or for each pipe to be insulated, the half-shells further having to be manufactured in a specialized works, then dispatched and stored in great volume by the user.
Finally the in situ casting process, although possessing the advantage of not necessitating a storage area, nor a mold, utilizes a special and sophisticated foaming machine which becomes fouled at every prolonged stoppage, and the chemical products utilized, which are stored in vats, must be utilized rapidly once these vats are opened by reason of their sensitivity to humidity, which prevents brief and spaced utilizations. Furthermore, the utilizer of this process must be perfectly acquainted with the technique of the foaming machine and the chemical behavior of polyurethane. Moreover, the casting of the foaming mixture of polyurethane, which is very liquid at the beginning, is always critical since frequently a part of the mixture leaks through holes or fissures in the flaps of the cardboard boxes intended for packaging, or the shuttering for insulation. These leakages can have serious consequences since the foaming mixture in the course of expansion is sticky and noxious, risking the causing of various damage. Finally, by reason of the state of the foam in the course of expansion no manipulation of this foam is possible, and thus it can only expand freely.
The present invention has the further purpose of diminishing these drawbacks.
More specifically, the invention is intended to provide an auto-expansible cushioning bag which permits of retaining all the advantages of in situ casting and of direct manufacture on the user's premises of molded objects such as cushioning corner pieces and half-shells of polyurethane foam, without a special installation.